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|United States Patent
February 3, 1998
Method of and arrangement for applying a surface pressure to workpieces
driven by a pressing band
For applying a surface pressure and temperature to pressing band-driven
workpieces a fluid pressure medium is accommodated in a pressure chamber
which is limited between a pressing band and a workpiece as well as seals
located therebetween, and the fluid pressure medium is subjected to
extensive forced movement in the pressure chamber which forms an action
Foreign Application Priority Data
De Brock; Raoul (Kortrijk, BE)
Firma Theodor Hymmen (Bielefeld, DE)
March 1, 1996|
|Jun 15, 1987[DE]||37 19 976.5|
|Current U.S. Class:
||100/310; 100/151; 100/308; 100/312; 156/583.5; 425/371 |
|Field of Search:
100/35,38,92,93 P,93 RP,151,152,153,154
U.S. Patent Documents
|3992135||Nov., 1976||Camp, III||425/371.
Primary Examiner: Soohoo; Tony G.
Attorney, Agent or Firm: Striker; Michael J.
Parent Case Text
This is a continuation of application Ser. No. 07/206,337 filed Jun. 10,
1988 now U.S. Pat. No. 5,558,016.
What is claimed as new and desired to be protected by Letters Patent is set
forth in the appended claims:
1. A method of applying a surface pressure and a temperature to workpieces
which are driven by a pressing band, comprising the steps of accommodating
a fluid pressure medium in an action zone which is limited between a
heating plate and a pressing band; producing a pressure in the fluid
pressure medium in the action zone so as to thereby apply a surface
pressure to the workpieces; moving the workpieces by the pressing band
along the action zone; producing a temperature in the fluid pressure
medium in the action zone so as to apply the temperature to the workpiece;
moving the fluid pressure medium in the action zone by moving means; and
additionally to said moving, producing a turbulent flow of the fluid
pressure medium in the action zone by turbulent flow producing means which
is separate from said moving means so as to positively act on the fluid
pressure medium and to produce the turbulent flow of the fluid pressure
medium which flows through the action zone and to thereby increase a heat
transfer to the workpieces.
2. A method as defined in claim 1, wherein said accommodating step includes
accommodating the pressure medium which is a gaseous pressure medium, said
producing step including moving the gaseous pressure medium with a speed
of 2-50 m/sec.
3. A method as defined in claim 2, wherein said producing step includes
moving the gaseous pressure medium with a speed of 20-40 m/sec.
4. A method as defined in claim 1, wherein said accommodating step includes
accommodating the pressure medium which is a liquid pressure medium, said
producing step including moving the liquid pressure medium with a speed of
5. A method as defined in claim 1, wherein said producing step includes
producing the turbulent flow of the fluid pressure medium directly in the
6. A method as defined in claim 1, wherein said producing step includes
producing the turbulent flow of the fluid pressure medium in a closed
circuit which includes the action zone.
7. A method as defined in claim 1; and further comprising controlling the
degree of temperature transfer from the fluid pressure medium to a
workpiece and including varying a flow speed of the fluid pressure medium.
8. A method as defined in claim 1; and further comprising controlling the
degree of temperature transfer from the pressure medium to a workpiece and
including varying a pressure of the fluid pressure medium.
9. A method as defined in claim 1; and further comprising controlling the
degree of temperature transfer from the pressure medium to a workpiece by
varying a speed of the fluid pressure medium and varying pressure of the
fluid pressure medium.
10. A method as defined in claim 1, wherein said producing includes
producing a turbulent flow of the fluid pressure medium in the action zone
by the turbulent flow producing means arranged in the action zone.
11. An arrangement for applying a surface pressure and temperature to
workpieces which are driven by a pressing band, comprising means forming
an action zone for accommodating a fluid pressure medium, said action zone
forming means including the pressing band and a heating plate with a seal
located between said pressing band and said plate; means for moving said
plate; means for moving said pressing band so that the workpieces are
moved by said pressing band along said action zone; means for supplying a
fluid pressure medium into said action zone so that the fluid pressure
medium is accommodated in said action zone under operational pressure and
moving the fluid pressure medium through said action zone; means for
generating a temperature in said plate; and additionally to said fluid
pressure medium supplying and moving means, separate means for producing a
turbulent flow of the fluid pressure medium in the action zone, so as to
positively act on the fluid pressure medium and to produce the turbulent
flow of the fluid pressure medium which flows through said action zone and
to thereby increase a heat transfer to the workpieces.
12. An arrangement as defined in claim 11, wherein said action zone has a
part with a flow cross-section which is greater than a flow cross-section
of a remaining part of said action zone.
13. An arrangement as defined in claim 11, wherein said action zone is
subdivided into at least two parts located one after the other and
arranged so that they have different flow speeds.
14. An arrangement as defined in claim 11, wherein said means for producing
a turbulent flow of the pressure medium in the action one is arranged in
said action zone.
BACKGROUND OF THE INVENTION
The present invention relates to a method of and arrangement for applying a
surface pressure to workpieces which are driven by a pressing band, for
example, continuously movable material webs, also in form of laminates or
Methods and arrangements of the above-mentioned general type are known in
the art. One of such methods and arrangements is disclosed in the German
document DE-OS 24 21 296. In this reference the surface pressure is
applied in an action zone which it limited at its one side by the pressing
band, under the action of the pressure of a gaseous or liquid pressure
medium acting in the action zone. A pressure chamber can be limited by a
peripherally closed substantially rectangular seal over the periphery of
the pressure chamber. At its one side, the pressure chamber is limited by
a rotatable pressing band, while at its rear side it is limited by a
pressing plate which simultaneously forms a heating plate for heating the
pressure medium in the action zone. Band presses which are provided with
such pressure chambers, for example, double-band presses, are also used
for heating and/or cooling of the movable workpieces.
When the fluid pressure media used here are for example air or oil,
controllability and sensitivity of adjustment are especially suitable.
However, a problem remains in that the pressure gas layer which is located
in the action zone between the rear side of the hot plate and the endless
pressing band in the pressure chamber acts in an insulating manner with
respect to the heat transfer. It has been proposed in the above-mentioned
German document to replace strongly insulating gaseous pressure media with
a liquid pressure medium, especially oil or liquid metal. While liquid
metals for this goal and in this area of application technically cannot be
considered as controllable, the use of oil does not bring radical
improvements since the heat conductivity of oil is maximum three times the
heat conductivity of air, and moreover it is susceptible to considerable
It has been also proposed to operate with heat bridges so as to insure a
direct heat conduction from the heating plate to the endless pressing band
through pressing shoes. This approach is disclosed in the German document
DE-PS 33 25 578. The pressing shoes which provide the heat conduction have
however considerable disadvantages. In addition to the very high force
requirement for driving the pressing band, metal wear also occurs on the
pressing shoes and therefore a reliable operation of the peripherally
closed seals for the pressure chamber becomes questionable.
Finally, another system has been proposed, in which a pressure medium is no
longer heated in the action zone but instead a steam (U.S. Pat. No.
2,135,763) or hot water (German document DE-OS 19 53 816) are supplied to
the action zone in a circulation circuit. The heating is performed outside
of the action zone, and the system operates with conventional supply
speeds or withdrawal speeds for steam and hot water. These systems have to
be considered as not suitable in praxis, since naturally the supplied hot
pressure medium is cooled during its movement through the action zone.
Since such action zones are relatively long, an unacceptable temperature
drop in transporting direction of the workpiece is produced from the inlet
to the outlet of the arrangement.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a method
of and an arrangement for applying a surface pressure to workpieces driven
by a pressing band, which avoids the disadvantages of the prior art.
More particularly, it is an object of the present invention to provide a
method of and an arrangement for applying a surface pressure to workpieces
which are driven by a pressing band, in which the heat transfer in the
action zone between a pressing plate which is formed as a heating or
cooling plate, and the pressing band is considerably improved.
In keeping with these objects and with others which will become apparent
hereinafter, one feature of the present invention resides, briefly stated,
in a method in which a fluid pressure medium in an action zone is
extensively forcedly moved by respective moving means.
It has been determined completely unexpectedly that by the relatively
extensive forced movement of the fluid medium under pressure in the action
zone, its property to transfer heat to the pressing band is
extraordinarily increased to such a degree that the heat transfer is much
better than for example when the above-mentioned known pressing shoes are
used. By the extensive forced movement in the action zone, the fluid
medium which is under the operational pressure takes over the function of
a heat transferring element from the heating plate which limits the action
zone, as a sender to the pressing band. It is to be understood that
exactly in the same way an extraordinarily improved cooling is produced
when the pressing plate is formed as a cooling plate. In this case the
heat flow propagates in an opposite direction from the pressing band.
In this system in which the heat transmitter and the heat receiver limit
the action zone, a temperature drop occurs exclusively in direction from
the heat transmitter to the heat receiver. The pressure medium acts only
as an agent or as an intermediate layer with a very high heat transfer
value resulting from the forced movement.
This also results in that the friction losses produced during the extensive
forced movement are completely converted into heat and contribute to
heating in the case of the heat transfer. In certain cases the heat
transmitter can be completely switched off at least temporarily.
In the inventive system the speed of the forced movement of the medium can
be used as a control value which allows very simple and very sensitive
controlling of the heat transfer. The respective given operational
pressure and the speed of transportation of the workpiece can be used as
parameters. It should be mentioned that in the event of operational
failures or product ends, the transmitting heat quantity drops abruptly,
since in this case by interruption of the forced movement and switching
off of respective heating, the medium in its immovable condition acts as
an insulation layer between the heating plate and the pressing band in the
action zone. It has been shown that this results only in a very low
inertia and particularly in no delays in the heat energy transmission.
The degree of the forced movement depends on operational pressure and the
degree of the desired heat transfer. In any case, it is desirable to move
the medium so extensively that a turbulent movement of the pressure medium
is produced. For gaseous media the movement speeds can be between 10 and
50 m/sec., preferably between 20 and 40 m/sec., while for liquid media the
movement speeds can be between 2 and 5 m/sec., preferably between 4 and 5
The extensive forced movement can be produced either exclusively in the
action zone, or in a circulating circuit which includes the action zone.
The devices for producing the extensive forced movement can include a fan
which can be integrated in the pressing and heating plate, several fans
with propellers extending into the pressure chamber, a rotary piston
blower, or a condenser.
The pressure chamber can be provided with a zone which has a smaller flow
cross-section as compared with a remaining part of the pressure chamber,
for increasing the speed of the pressure medium in the pressure chamber.
The novel features which are considered as characteristic for the invention
are set forth in particular in the appended claims. The invention itself,
however, both as to its construction and its method of operation, together
with additional objects and advantages thereof, will be best understood
from the following description of specific embodiments when read in
connection with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a view schematically showing an arrangement for applying a
surface pressure to a workpiece which is driven by a pressing band, in
accordance with the present invention;
FIG. 2 is a schematic view showing the arrangement for applying a surface
pressure in accordance with another embodiment of the present invention;
FIG. 3 is a view schematically showing the arrangement for applying the
surface pressure in accordance with a further embodiment of the present
DESCRIPTION OF THE PREFERRED EMBODIMENTS
An arrangement for applying a surface pressure as well as heat to pressing
band-driven workpieces has a rotatable pressing band 1 which is
conventionally composed of steel and runs over deviating rollers 2. The
pressing band 1 continuously moves workpieces such as, for example,
material webs also in form of laminates, along an action zone 4 which in
the embodiment shown in FIG. 1 is formed as a pressure chamber. The
pressure chamber is limited by the pressing band 1 at its one side, by a
pressing and heating plate 5 at its opposite side, and also known
peripherally closed or circular special seals 6.
In the action zone 4 or the pressure chamber, the required surface pressure
is produced in a known manner, for example, by a gaseous pressure medium
which is under the operational pressure. The pressure chamber is in
communication with a not shown compressor in a conventional manner, which
operates so as to continuously compensate leakage losses from the pressure
chamber. A heating device 7 is located in the pressing and heating plate
5. In addition, a gaseous medium which is located in the action zone under
pressure is subjected to an extensive forced movement by means of a gas
displacing device. In the shown embodiment, the pressing and heating plate
5 has relatively great dimensions, and a fan 8 which forms the
above-mentioned gas displacing device is integrated in it. The fan 8
communicates via an integrated pressure and suction conduit 9 with the
action zone 4 and forcedly displaces the pressure medium which is
accommodated under pressure in the action zone 4 in a very efficient
manner. In particular, the forced displacement of the gaseous medium can
be performed so that a turbulent flow is produced in the action zone 4 and
leads to an extremely high heat transfer between the pressing and heating
plate 5 and the pressing band 2.
The degree of the heat transfer can be controlled both by the operational
pressure and especially by the flow speed in a very sensitive manner. In
the embodiment shown in FIG. 1 it is achieved in very simple manner with
the following approach. A stronger heating in a first portion of the
action zone 4, as considered in direction of transportation of the
workpiece 3, is produced as compared with a rear portion of the action
zone 4 of the pressure chamber. This is achieved by a projecting shoulder
which is formed in the pressing and heating plate 5 so that the first
portion of the action zone 4 identified with reference 4a has a narrower
cross-section and therefore a higher flow speed of the gaseous medium
which passes therethrough.
In the embodiment shown in FIG. 2 which actually has the same construction
as the embodiment of FIG. 1, a pressing and heating plate 5a is provided
with one or more gas displacement devices depending on the length of the
action zone 4. In the embodiment of FIG. 2 there are two such gas
displacement devices which are formed as fans 8a with rotatable propellers
8b. The propeller 8b is formed as a flat propeller and at least partially
extends into the action zone 4.
The arrangements for applying surface pressure in accordance with FIGS. 1
and 2 have a compact construction which are characterized by very low heat
losses and avoid previously existing connection problems.
The arrangement shown in FIG. 3 has the same basic structure as in the
previous embodiments. It comprises a front pressing and heating plate 5b
with supply and withdrawal conduits 10 which extend from the action zone 4
under the pressing and heating plate 5b outwardly of the plate. A fan 8 is
arranged in the conduit 10, and further a compressor 11 is connected with
the conduit 10 for continuously compensating leakage losses. The gaseous
medium under the operational pressure is also directly heated here in the
action zone 4, and its extensive forced movement in this action zone 4
serves for extraordinary increase of the heat transfer properties.
In the embodiment of FIG. 3 an action zone 4b is arranged after the action
zone 4 which serves for heating the pressing band 1 and thereby the
workpiece 3. The action zone 4b has basically the same construction as the
action zone 4, however here the heat transfer direction is reversed. In
other words, the action zone 4b is a cooling zone which has a pressing and
cooling plate 5c provided with a cooling device 7a. In exactly the same
manner, for considerable increase in the cooling properties, the gaseous
medium which is under pressure in the action zone 4a is extensively
displaced. This is performed by a fan 8. Also a compressor 11 is provided
in this action zone. A rotary piston blower or a condensor can also be
used as forced displacement devices. When the arrangement operates with
liquid pressure media, pumps can be used instead of the fans described
In accordance with the inventive method for applying a surface pressure and
transferring heat to the pressing band-driven workpieces, the surface
pressure is produced in the sealed action zone by the pressure of a fluid
pressure medium and in the action zone is heated or cooled in a
conventional manner, and in addition the pressure medium which is under
operational pressure is extensively forcedly displaced in the action zone.
In accordance with the advantageous embodiment, the forced movement is
performed so extensively that the pressure medium which is accommodated in
the action zone under the operational pressure forms turbulent flows. Flow
speeds of the media used in the inventive arrangement are approximately
20-40 m/sec. for gaseous pressure media and 4-5 m/sec. for liquid pressure
medium. These speeds are especially advantageous for the operation of the
inventive arrangement. The extensive forced movement can be performed
locally, exclusively in the action zone. On the other hand, it is possible
to provide a forced circulation in a closed circuit which includes the
The degree of the heat transfer can be controlled in a very sensitive
manner by changing the flow speed and/or the pressure of the pressure
medium in the action zone.
The forced movement of the gaseous pressure medium can be performed with
the speed of 2-50 m/sec, preferably from 20-40 m/sec in the case of
gaseous pressure medium and from 4-5 m/sec, in the case of liquid
This extensive forced movement of the fluid pressure medium is finished
when the pressing band is stopped.
For obtaining the results produced by the present invention it is not
necessary to guide the pressure medium in a closed circuit. It is possible
to provide in the region of the seals which peripherally limit the
pressure chamber, an increased loss of gaseous pressure medium and to
considerably replace the pressure medium flowing out of the pressure
chamber by supplying a corresponding quantity of pressure medium into the
It will be understood that each of the elements described above, or two or
more together, may also find a useful application in other types of
constructions differing from the types described above.
While the invention has been illustrated and described as embodied in an
arrangement for applying a surface pressure and heat to pressing
band-driven workpieces, it is not intended to be limited to the details
shown, since various modifications and structural changes may be made
without departing in any way from the spirit of the present invention.
Without further analysis, the foregoing will so fully reveal the gist of
the present invention that others can, by applying current knowledge,
readily adapt it for various applications without omitting features that,
from the standpoint of prior art, fairly constitute essential
characteristics of the generic or specific aspects of this invention.